A: Would you ever expect to walk into a shop, pick-up an item and say 'I'll pay for it later'?
No! Therefore, I think it is prudent to state the expectionally obvious - never send ANY items to ANYONE without having firstly received the money in advance. Trust is a wonderful and declining thing, but that was just plain stupidity. I bet you have regretted it everyday since. So would I have, so let go of it and move on. I can guarantee that you'll never do it again.
B: Thank you for drawing it to the attention of others on the site and in the Atari community, but I for one think that most people would realise in advance that rule A applies to to rule B...